#include <algorithm>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <numeric>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <ranges>
#include <iomanip>
using namespace std;
using ll = long long;

auto range(int n) { return views::iota(0, n); }

template<class T, class U> ostream& operator<<(ostream& os, const pair<T, U>& p){ return os << "{" << p.first << ", " << p.second << "}"; }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& obj) { os << "{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }
template<typename T> ostream& operator<<(ostream& os, const set<T>& obj) { os << "set{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }
template<typename T, typename U> ostream& operator<<(ostream& os, const map<T, U>& obj) { os << "map{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }

#ifdef ONLINE_JUDGE
#define dump(expr) ;
#else
#define dump(expr) { cerr << "\033[33m#L" << __LINE__ << ": " << expr << "\033[39m" << endl; }
#endif

const int mod = 1000000007;
struct mint {
  ll x;
  mint(ll x_ = 0) : x((x_ % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint &a) { if ((x += a.x) >= mod) x -= mod; return *this; }
  mint &operator-=(const mint &a) { if ((x += mod - a.x) >= mod) x -= mod; return *this; }
  mint &operator*=(const mint &a) { (x *= a.x) %= mod; return *this; }
  mint operator+(const mint &a) const { mint res(*this); return res += a; }
  mint operator-(const mint &a) const { mint res(*this); return res -= a; }
  mint operator*(const mint &a) const { mint res(*this); return res *= a; }
  mint pow(ll t) const { if (!t) return 1; mint a = pow(t >> 1); a *= a; if (t & 1) a *= *this; return a; }
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint &a) { return (*this) *= a.inv(); }
  mint operator/(const mint &a) const { mint res(*this); return res /= a; }
  friend ostream &operator<<(ostream &os, const mint &m) { os << m.x; return os; }
  friend istream &operator>>(istream &is, mint &m) { is >> m.x; return is; }
};

// code is from noya2
// sum[ i in [0,n) ] floor( (a * i + b) / m )
template<typename T>
T floor_sum(T n, T m, T a, T b){
    if (n <= 0) return 0;
    T ans = 0;
    while (true){
        T da = a / m;
        ans += (n >> 1) * ((n - 1) | 1) * da;
        a -= da * m;
        T db = b / m;
        ans += n * db;
        b -= db * m;
        T y_max = a * n + b;
        if (y_max < m) break;
        T dy_max = y_max / m;
        n = dy_max;
        b = y_max - dy_max * m;
        swap(m, a);
    }
    return ans;
}

ll solve() {
  int n, m; cin >> n >> m;
  vector<int> as(n), bs(m);
  for (int i : range(n)) cin >> as[i];
  for (int i : range(m)) cin >> bs[i];

  mint res = 0;
  map<pair<int, int>, mint> memo;
  for (ll a : as)
  for (ll b : bs) {
    if (!memo.count({a, b})) {
      memo[{a, b}] = floor_sum(b + 1, b, a, 0LL);
    }
    res += mint(2) * memo[{a, b}];
    /*
    for (int k = 1; k <= b; ++k) {
      res += mint(2) * ((ll)a * k / b);
    }
    */
  }
  return res.x;
}

int main() {
  cout << fixed << setprecision(12);
  cout << solve() << endl;
}